Blower fan



Nov. 10, 1942. A. A. CRlQUl 2,301,857

BLOWER FAN Filed Jan. 12, 1940 2 Sheets-Sheet l l O O I 29 Z8 ff \NVENTOR AlberyA. Cmqui,

55 ATTORN EYS @uw, MMT $44M tive, sectional Patented Nov. 10, 1942 UNITEDIST'ATES PATENT OFFICE Albert Al Criqui, Kenmore, N. Y., assignor to Buffalo Forge Company, Buffalo, N. Y., a corporav tionof New York Application January 12, 1940, Serial No. 313,598

" a i i 2 Claims. ((1230-1151) Myinventiori relates in general-to blower fans andmore particularly to that type of fan having what is known as a. mixedflow wheel which is a combination of the centrifugaland propel lertypewheels. it

One of the principal objects of myinvention has been to provide a wheel for fans of this typehavin'g blades, each provided with a back ward-curve at the tip or outlet portion thereof forstabilizing the pressuf u f a Produced bythefan. a ,t

A further object has beento provide a blade for fan'wh'eels 1 having" a curve-shaped inlet portion which greatly increases the velocity of the air entering thefan and therefore the-capacity thereof. 1

Another object has been to provide a 'wheel for a fan' of-this type having a reducedinlet whereby the pressure characteristic and efficiency of the fan is increased. v 1

A further-object =is to provide a wheel for' fans-of thistype-which -shall be very effioient inoperatiomw- 1 'Another object has been to provide a fan wheel" which, because of itsstabili'ty of performance,-

can readily be' used in parallel arrangement several fan units. I: i

Moreover; my wheel-can be clency while maintaining a low noise level.-

Furthermore, because of my invention, the fan I wheel may be made of light material while main tainingnecessary rigidity. 1

The above objects and 'advantages have been Fig. 3 is: an enlarged, fragmentarypperspecview showing the blade construc'- tion.-: 1

Fig. 4 is'a diagrammatic view showing the cylinders on which the curved surfaces of the blades are generated. I it F1355 isa fragmentary viewshowing a slight.-

the accom- I formed with two inlet eyes-"IL The outlet of the' fan is represented at l2. The fan wheel bracktsili supported thereby.-

Since-my invention isshown applied to a dou- 34 ble inlet fan, the fan wheel is therefore provided with a central disc 20 at each side of which are arranged the fan blades 2|. The disc 20 is preferably carried by flanges 25 and 26 arranged on each side thereof and rigidly mounted upon the drive shaft H.

Each of the blades 2| of my invention comprises a substantially flat .body portion 22, a curved inlet portion 23 and a curved tip portion 24. In carrying out my invention the tip portion' 24 of each of the blades is curved backwardly, as clearly shown in the drawings which servesto reduce and stabilize the pressure of the air as it leaves the blades. The formation of the blade also increases the efiiciency of the fan.

The inlet portion 23 of each of the blades is of forwardly curved formation, whereby the air at the wheel inlet 3| is greatly increased in velocity which, in turn, increases the capacity of the fan. The curved surfaces of the inlet portion 23 and of the tip portion 24 of the blades are each preferably generated on a cylinder; and, for convenience of illustration, these cylinders are shown in Fig. 4 of the drawings by broken lines. The cylinder on which the surface of the inlet portion is generated is represented by the cylinder 31 and the cylinder on which the tip portion is generated is represented by the cylinder 38. The substantially fiat body portions of my blades extend radially outward and have their inner edges 30 curved outwardly toward the peripheral edges of the inlet portions 23 or wheelinlet3l.

In order to improve the pressure characteristic of my fan and to increase its efilciency, the fan inlet 3| is reduced in diameter by cutting away the outer corners of the blades at the inlet portions, as shown, and providing a shroud ring 32 at the cut-away portions. Th shroud ring has a diameter somewhat less than the diameter of the periphery of the wheel. The shroud ring is provided with an outwardly extending flange 33 which is preferably inclined inwardly toward the disc 20, as shown in the drawings, and which serves to increase the velocity of the air passing outwardly in radial direction toward the periphery of the wheel. The blades are provided with flanges 21, 28 and '29 which are suitably secured, respectively, to the shroud ring 32, to the flange 33, and to the disc 20, thereby making a very rigid structure and permitting the use of relatively thin, light material for blade construction.

My fan is provided with the usual seal ring which is carried by the casing I0 and which surrounds the shroud ring 32, This ring is slightly larger in diameter than the wheel and the inner edge 35 thereof is so located with respect to the outer edge 35 of the flange 33 that the seal duct 40 formed therebetween may be reduced to a minimum. Owing to the fact that the inlet of the fan is reduced with the resulting reduction in diameter of the shroud ring 32, there is considerable space between the shroud ring and the seal plate 34 so that any tendency for the wheel to touch the seal plate is completely avoided.

In the modified form of construction shown in Fig. 5 the shroud ring 4| is of substantially the same diameter as the peripheral diameter of the wheel which is coincident with the blade edge 42. The diameter of the inlet of the fan wheel in this form of invention is therefore substantially the same as the diameter of the periphery thereof. In this form, the blade 43 has a substantially flat radially-disposed body portion 44, a forwardly curved inlet portion 45, and a rearwardly curved tip portion 46.

From the foregoing it will be seen that as the fan wheel is rotated in the direction of the arrow shown in Figs. 1 and 3, the air is drawn in through the inlet eyes ll of the fan casing l0 and into the inlets 3| of the fan wheel. The forwardly curved inlet portions 23 of the blades serve to catch the air and cause it to be drawn into the wheel at greatly increased velocity with resulting increased capacity and efllciency. This air striking the surfaces of the flat body portions 22 of the blades is caused to move outwardly in radial direction and under the influence of centrifugal force. The air which passes outwardly in radial direction over the area covered by the inclined annular flange 33 will have its velocity further increased by contact with such flange. As the air reaches the outer peripheral edge of the tip portions 24 of the blades, the kinetic energy of the air is reduced to a minimum by passage over the backwardly curved surfaces of such tip portions, thereby reducing the velocity of the air and stabilizing the pressure with a resulting increase in efiiciency of operation.

While I have found that the reduction in diameter of the fan wheel inlet increases the efficiency of the wheel, it is obvious that the wheel inlet may be of substantially the same diameter as the periphery of the wheel, as shown by the modified form of invention. It is preferable to have the flange 33 extending outwardly from the shroud ring 32 either made separate therefrom or integral therewith and arranged at an angle to each other but substantially the same results may be accomplished by having these two parts made in one single piece ring and formed with a concave outer surface. Furthermore, while the invention has been shown as applied to a double inlet fan, it is obvious that it can be used with fans having but one inlet.

Having thus described my invention, what I claim is:

1. A blower fan having a wheel provided with a plurality of blades, an inlet, a seal plate at said inlet, and an annular flange extending outwardly from the wheel inlet toward the outer periphery of the wheel, said seal plate being substantially cylindrical in form and substantially larger in diameter than the diameter of the wheel and surrounding said flange in interspaced relation, each of said blades being fastened to said flange and having a forwardly curved inlet portion forming a part of a cylinder having its axis substantially perpendicular to the axis of the wheel, a backwardly curved tip portion forming a part of a cylinder having its axis substantially parallel to the axis of the wheel, and a substantially fiat portion joining said inlet and tip portions.

2. A blower fan having a wheel provided with a plurality of blades, an inlet for said wheel, said inlet having a diameter smaller than the outer diameter of the wheel, an annular flange carried by said wheel and extending outwardly from the wheel inlet toward the outer periphery of the wheel, each of said blades being fastened to said flange and having a forwardly curved inlet portion forming a part of a cylinder having its axis substantially perpendicular to the axis of the wheel, a backwardly curved tip portion forming a part of a cylinder having its axis substantially parallel to the axis of the wheel, and a substantially flat portion joining said inlet and tip portions and being substantially radially disposed.

ALBERT A. CRIQUI. 

